The present invention relates to a cooling and heating system utilizing solar heat and comprising a heat collector for heating a circulating heat medium with solar heat, an absorption refrigerator operable with the heat medium heated by the heat collector and serving as a generating heat source to provide a chilled medium, and an air-conditioning unit for circulating the chilled medium or the heated medium alternatively therethrough to cool or heat the space to be air-conditioned.
Conventional cooling and heating systems of this type mainly resort to the use of the solar heat collected by a heat collector and serving as a cooling and heating energy source and therefore have the following problems:
(1) Although the air-conditioning load varies greatly throughout the year, the heat collector as well as the refrigerator must have a considerably large capacity adapted for the maximum load during the year. PA1 (2) When the air-conditioning load is small, accordingly, the heat collector and the refrigerator are unable to exhibit their abilities to the greatest possible extent, invariably failing to permit the system to achieve a high thermal efficiency all the year round. PA1 (3) Consequently there arises the necessity of using a heat accumulator of fairly large capacity for storing the excess of heat when the air-conditioning load is small despite sufficient sunshine. PA1 (4) There is the inherent requirement that the heat medium for operating the refrigerator must have a temperature of at least about 82.degree. C. Additionally an absorption refrigerator, if used for the system, must be fully operable with solar heat to provide a chilled medium at an optimum temperature of about 7 to about 8.degree. C. as requied for air conditioning. The heat medium needs then to have a considerably high temperature of at least about 88.degree. C. Thus when the heat collector is unable to give the desired amount of heat medium owing to insufficient sunshine, there arises a need to use an auxiliary heat source in addition to solar heat. Further when no sunshine is available, the refrigerator must be operated solely with the auxiliary heat source. The refrigerator nevertheless is inherently as low as about 0.65 to about 0.68 in coefficient of performance (C.O.P.) and therefore necessitates a fairly large auxiliary heat source, which renders the refrigerator very inefficient to operate.
Accordingly the conventional systems are not fully satisfactory in overall thermal efficiency, require a high running cost and involve the problem that the relatively great investment in equipment is not completely repayable.